Despite the "Legacy" tag, some community reviewers and players noted subtle differences after patches: Defensive Tweaks
But the real shock came at halftime.
Without the update, you are playing with July 2020 squads. With the update, you get the winter transfer window. For offline players, this changes the dynamic of Career Mode. Playing as Liverpool without Thiago or as Dortmund without Haaland (pre-transfer) feels broken. The update fixes this. fifa 21 legacy edition switch nsp update better